Injectable Polymeric Cytokine-Binding Nanowires Are Effective Tissue-Specific Immunomodulators

NK cell-based tumor immunotherapy

Natural killer (NK) cells display a unique inherent ability to identify and eliminate virus-infected cells and tumor cells. They are particularly powerful for elimination of hematological cancers, and have attracted considerable interests for therapy of solid tumors. However, the treatment of solid tumors with NK cells are less effective, which can be attributed to the very complicated immunosuppressive microenvironment that may lead to the inactivation, insufficient expansion, short life, and the poor tumor infiltration of NK cells. Fortunately, the development of advanced nanotechnology has provided potential solutions to these issues, and could improve the immunotherapy efficacy of NK cells. In this review, we summarize the activation and inhibition mechanisms of NK cells in solid tumors, and the recent advances in NK cell-based tumor immunotherapy boosted by diverse nanomaterials. We also propose the challenges and opportunities for the clinical application of NK cell-based tumor immunotherapy.

Precise surface functionalization of PLGA particles for human T cell modulation

The biofunctionalization of synthetic materials has extensive utility for biomedical applications, but approaches to bioconjugation typically show insufficient efficiency and controllability. We recently developed an approach by building synthetic DNA scaffolds on biomaterial surfaces that enables the precise control of cargo density and ratio, thus improving the assembly and organization of functional cargos. We used this approach to show that the modulation and phenotypic adaptation of immune cells can be regulated using our precisely functionalized biomaterials. Here, we describe the three key procedures, including the fabrication of polymeric particles engrafted with short DNA scaffolds, the attachment of functional cargos with complementary DNA strands, and the surface assembly control and quantification. We also explain the critical checkpoints needed to ensure the overall quality and expected characteristics of the biological product. We provide additional experimental design considerations for modifying the approach by varying the material composition, size or cargo types. As an example, we cover the use of the protocol for human primary T cell activation and for the identification of parameters that affect ex vivo T cell manufacturing. The protocol requires users with diverse expertise ranging from synthetic materials to bioconjugation chemistry to immunology. The fabrication procedures and validation assays to design high-fidelity DNA-scaffolded biomaterials typically require 8 d.

Harnessing Biomaterials for Immunomodulatory-Driven Tissue Engineering

Abstract

The immune system plays a crucial role during tissue repair and wound healing processes. Biomaterials have been leveraged to assist in this in situ tissue regeneration process to dampen the foreign body response by evading or suppressing the immune system. An emerging paradigm within regenerative medicine is to use biomaterials to influence the immune system and create a pro-reparative microenvironment to instigate endogenously driven tissue repair. In this review, we discuss recent studies that focus on immunomodulation of innate and adaptive immune cells for tissue engineering applications through four biomaterial-based mechanisms of action: biophysical cues, chemical modifications, drug delivery, and sequestration. These materials enable augmented regeneration in various contexts, including vascularization, bone repair, wound healing, and autoimmune regulation. While further understanding of immune-material interactions is needed to design the next generation of immunomodulatory biomaterials, these materials have already demonstrated great promise for regenerative medicine.

Lay Summary

The immune system plays an important role in tissue repair. Many biomaterial strategies have been used to promote tissue repair, and recent work in this area has looked into the possibility of doing repair by tuning. Thus, we examined the literature for recent works showcasing the efficacy of these approaches in animal models of injuries. In these studies, we found that biomaterials successfully tuned the immune response and improved the repair of various tissues. This highlights the promise of immune-modulating material strategies to improve tissue repair.

Customized Multifunctional Peptide Hydrogel Scaffolds for CAR-T-Cell Rapid Proliferation and Solid Tumor Immunotherapy

CAR-T-cell therapies must be expanded to obtain a large number of effector cells quickly, and the current technology cannot address this challenge. A longer operational time would lose or alter the function and phenotype of CAR-T cells in response to therapy, and it also causes a loss in the optimal treatment time for patients. At present, lower survival time and homing efficiency reduce the antitumor effect of CAR-T in vivo. But nobody has solved these two issues in one system, which has a similar microenvironment of lymphoid organs to activate/expand cell delivery for immunotherapy. Here, we generated artificial, customized immune cell matrix scaffolds based on a self-assembling peptide to preserve and augment the cell phenotype in light of the characteristics of CAR-T. The all-in-one nanoscale matrix scaffolds reduced the processing time of CAR-T to 3 days and resulted in over a 10-fold increase compared with the traditional protocol. The cells were combined to modulate mechanotransduction and chemical signals, and the mimic matrix scaffolds showed optimal stiffness and adhesive ligand density, thereby accelerating CAR-T-cell proliferation. Meanwhile, engineering CAR-T-secreted intrinsic PD-1 blocking single-chain variable fragments (scFv) further increased cell proliferation and cytotoxicity by resisting the self and tumor microenvironment in a paracrine and autocrine manner. Local delivery of CAR-T cells from the scaffolds significantly enabled long-term retention, suppressed tumor growth, and increased infiltration of effector T cells compared with traditional CAR-T treatment. The application of bioengineering and genetic engineering approaches has led to the development of rapid culture environments that can control matrix scaffold properties for CAR-T-cell and cancer immunotherapies.

Current Applications of Polycaprolactone as a Scaffold Material for Heart Regeneration

Despite numerous advances in treatments for cardiovascular disease, heart failure (HF) remains the leading cause of death worldwide. A significant factor contributing to the progression of cardiovascular diseases into HF is the loss of functioning cardiomyocytes. The recent growth in the field of cardiac tissue engineering has the potential to not only reduce the downstream effects of injured tissues on heart function and longevity but also re-engineer cardiac function through regeneration of contractile tissue. One leading strategy to accomplish this is via a cellularized patch that can be surgically implanted onto a diseased heart. A key area of this field is the use of tissue scaffolds to recapitulate the mechanical and structural environment of the native heart and thus promote engineered myocardium contractility and function. While the strong mechanical properties and anisotropic structural organization of the native heart can be largely attributed to a robust extracellular matrix, similar strength and organization has proven to be difficult to achieve in cultured tissues. Polycaprolactone (PCL) is an emerging contender to fill these gaps in fabricating scaffolds that mimic the mechanics and structure of the native heart. In the field of cardiovascular engineering, PCL has recently begun to be studied as a scaffold for regenerating the myocardium due to its facile fabrication, desirable mechanical, chemical, and biocompatible properties, and perhaps most importantly, biodegradability, which make it suitable for regenerating and re-engineering function to the heart after disease or injury. This review focuses on the application of PCL as a scaffold specifically in myocardium repair and regeneration and outlines current fabrication approaches, properties, and possibilities of PCL incorporation into engineered myocardium, as well as provides suggestions for future directions and a roadmap toward clinical translation of this technology.

Bioinspired Polymeric High Aspect Ratio Particles with Asymmetric Janus Functionalities

Polymeric particles with intricate morphologies and properties have been developed based on bioinspired designs for applications in regenerative medicine, tissue engineering, and drug delivery. However, the fabrication of particles with asymmetric functionalities remains a challenge. Janus polymeric particles are an emerging class of material with asymmetric functionalities; however, they are predominantly spherical in morphology, made from non-biocompatible materials, and made using specialized fabrication techniques. We therefore set out to fabricate nonspherical Janus particles inspired by high aspect ratio filamentous bacteriophage using polycaprolactone polymers and standard methods. Janus high aspect ratio particles (J-HARPs) were fabricated with a nanotemplating technique to create branching morphologies selectively at one edge of the particle. J-HARPs were fabricated with maleimide handles and modified with biomolecules such as proteins and biotin. Regioselective modification was observed at the tips of J-HARPs, likely owing to the increased surface area of the branching regions. Biotinylated J-HARPs demonstrated cancer cell biotin receptor targeting, as well as directional crosslinking with spherical particles via biotin-streptavidin interactions. Lastly, maleimide J-HARPs were functionalized during templating to contain amines exclusively at the branching regions and were dual-labeled orthogonally, demonstrating spatially separated bioconjugation. Thus, J-HARPs represent a new class of bioinspired Janus material with excellent regional control over biofunctionalization.

DNA scaffolds enable efficient and tunable functionalization of biomaterials for immune cell modulation

Biomaterials can improve the safety and presentation of therapeutic agents for effective immunotherapy, and a high level of control over surface functionalization is essential for immune cell modulation. Here, we developed biocompatible immune cell-engaging particles (ICEp) that use synthetic short DNA as scaffolds for efficient and tunable protein loading. To improve the safety of chimeric antigen receptor (CAR) T cell therapies, micrometre-sized ICEp were injected intratumorally to present a priming signal for systemically administered AND-gate CAR-T cells. Locally retained ICEp presenting a high density of priming antigens activated CAR T cells, driving local tumour clearance while sparing uninjected tumours in immunodeficient mice. The ratiometric control of costimulatory ligands (anti-CD3 and anti-CD28 antibodies) and the surface presentation of a cytokine (IL-2) on ICEp were shown to substantially impact human primary T cell activation phenotypes. This modular and versatile biomaterial functionalization platform can provide new opportunities for immunotherapies.

Engineering the drug carrier biointerface to overcome biological barriers to drug delivery

Micro and nanoscale drug carriers must navigate through a plethora of dynamic biological systems prior to reaching their tissue or disease targets. The biological obstacles to drug delivery come in many forms and include tissue barriers, mucus and bacterial biofilm hydrogels, the immune system, and cellular uptake and intracellular trafficking. The biointerface of drug carriers influences how these carriers navigate and overcome biological barriers for successful drug delivery. In this review, we examine how key material design parameters lead to dynamic biointerfaces and improved drug delivery across biological barriers. We provide a brief overview of approaches used to engineer key physicochemical properties of drug carriers, such as morphology, surface chemistry, and topography, as well as the development of dynamic responsive materials for barrier navigation. We then discuss essential biological barriers and how biointerface engineering can enable drug carriers to better navigate and overcome these barriers to drug delivery.

Networks of High Aspect Ratio Particles to Direct Colloidal Assembly Dynamics and Cellular Interactions

Injectable colloids that self-assemble into three-dimensional networks are promising materials for applications in regenerative engineering, as they create open systems for cellular infiltration, interaction, and activation. However, most injectable colloids have spherical morphologies, which lack the high material-biology contact areas afforded by higher aspect ratio materials. To address this need, injectable high aspect ratio particles (HARPs) were developed that form three-dimensional networks to enhance scaffold assembly dynamics and cellular interactions. HARPs were functionalized for tunable surface charge through layer-by-layer electrostatic assembly. Positively charged Chitosan-HARPs had improved particle suspension dynamics when compared to spherical particles or negatively charged HARPs. Chit-HARPs were used to improve the suspension dynamics and viability of MIN6 cells in three-dimensional networks. When combined with negatively charged gelatin microsphere (GelMS) porogens, Chit-HARPs reduced GelMS sedimentation and increased overall network suspension, due to a combination of HARP network formation and electrostatic interactions. Lastly, HARPs were functionalized with fibroblast growth factor 2 (FGF2) to highlight their use for growth factor delivery. FGF2-HARPs increased fibroblast proliferation through a combination of 3D scaffold assembly and growth factor delivery. Taken together, these studies demonstrate the development and diverse uses of high aspect ratio particles as tunable injectable scaffolds for applications in regenerative engineering.

Chemical Strategies to Boost Cancer Vaccines

Personalized cancer vaccines (PCVs) are reinvigorating vaccine strategies in cancer immunotherapy. In contrast to adoptive T-cell therapy and checkpoint blockade, the PCV strategy modulates the innate and adaptive immune systems with broader activation to redeploy antitumor immunity with individualized tumor-specific antigens (neoantigens). Following a sequential scheme of tumor biopsy, mutation analysis, and epitope prediction, the administration of neoantigens with synthetic long peptide (SLP) or mRNA formulations dramatically improves the population and activity of antigen-specific CD4+ and CD8+ T cells. Despite the promising prospect of PCVs, there is still great potential for optimizing prevaccination procedures and vaccine potency. In particular, the arduous development of tumor-associated antigen (TAA)-based vaccines provides valuable experience and rational principles for augmenting vaccine potency which is expected to advance PCV through the design of adjuvants, delivery systems, and immunosuppressive tumor microenvironment (TME) reversion since current personalized vaccination simply admixes antigens with adjuvants. Considering the broader application of TAA-based vaccine design, these two strategies complement each other and can lead to both personalized and universal therapeutic methods. Chemical strategies provide vast opportunities for (1) exploring novel adjuvants, including synthetic molecules and materials with optimizable activity, (2) constructing efficient and precise delivery systems to avoid systemic diffusion, improve biosafety, target secondary lymphoid organs, and enhance antigen presentation, and (3) combining bioengineering methods to innovate improvements in conventional vaccination, "smartly" re-educate the TME, and modulate antitumor immunity. As chemical strategies have proven versatility, reliability, and universality in the design of T cell- and B cell-based antitumor vaccines, the union of such numerous chemical methods in vaccine construction is expected to provide new vigor and vitality in cancer treatment.

TiO2-Based Nanotopographical Cues Attenuate the Restenotic Phenotype in Primary Human Vascular Endothelial and Smooth Muscle Cells

Coronary and peripheral stents are implants that are inserted into blocked arteries to restore blood flow. After stent deployment, the denudation of the endothelial cell (EC) layer and the resulting inflammatory cascade can lead to restenosis, the renarrowing of the vessel wall due to the hyperproliferation and excessive matrix secretion of smooth muscle cells (SMCs). Despite advances in drug-eluting stents (DES), restenosis remains a clinical challenge and can require repeat revascularizations. In this study, we investigated how vascular cell phenotype can be modulated by nanotopographical cues on the stent surface, with the goal of developing an alternative strategy to DES for decreasing restenosis. We fabricated TiO2 nanotubes and demonstrated that this topography can decrease SMC surface coverage without affecting endothelialization. In addition, to our knowledge, this is the first study reporting that TiO2 nanotube topography dampens the response to inflammatory cytokine stimulation in both endothelial and smooth muscle cells. We observed that compared to flat titanium surfaces, nanotube surfaces attenuated tumor necrosis factor alpha (TNFα)-induced vascular cell adhesion molecule-1 (VCAM-1) expression in ECs by 1.8-fold and decreased TNFα-induced SMC growth by 42%. Further, we found that the resulting cellular phenotype is sensitive to changes in nanotube diameter and that 90 nm diameter nanotubes leads to the greatest magnitude in cell response compared to 30 or 50 nm nanotubes.

An Injectable Cytokine Trap for Local Treatment of Autoimmune Disease

Systemic cytokine therapy is limited by toxicity due to activation of unwanted immune cells in off-target tissues. Injectable nanomaterials that interact with the immune system have potential to offer improved pharmacokinetics and cell specificity compared to systemic cytokine therapy by instead capturing and potentiating endogenous cytokine. Here we demonstrate the use of high aspect ratio polycaprolactone nanowires conjugated to cytokine-binding antibodies that assemble into porous matrices when injected into the subcutaneous space. Nanowires are well tolerated in vivo over several weeks, incite minimal foreign body response and resist clearance. Nanowires conjugated with JES6-1, an anti-interleukin-2 (IL-2) antibody, were designed to capture endogenous IL-2 and selectively activate tissue resident regulatory T cells (Tregs). Together these nanowire-antibody matrices were capable of sequestering endogenous IL-2 in the skin and were successful in rebalancing local immune compartments to a more suppressive, Treg-mediated phenotype in both wild type and transgenic murine autoimmune disease models.

Recent development in biodegradable nanovehicle delivery system-assisted immunotherapy

A schematic illustration of BNDS biodegradation and release antigen delivery for assisting immunotherapy.